SharedBuffer: Split the creation and share steps

This allows us to seal a buffer *before* anyone else has access to it
(well, ok, the creating process still does, but you can't win them all).

It also means that a SharedBuffer can be shared with multiple clients:
all you need is to have access to it to share it on again.

Libraries/LibAudio/AClientConnection.cpp

@@ -19,7 +19,7 @@ void AClientConnection::handshake()
 
 void AClientConnection::play(const ABuffer& buffer)
 {
-    auto shared_buf = SharedBuffer::create(server_pid(), buffer.size_in_bytes());
+    auto shared_buf = SharedBuffer::create_with_size(buffer.size_in_bytes());
     if (!shared_buf) {
         dbg() << "Failed to create a shared buffer!";
         return;
@@ -27,6 +27,7 @@ void AClientConnection::play(const ABuffer& buffer)
 
     memcpy(shared_buf->data(), buffer.data(), buffer.size_in_bytes());
     shared_buf->seal();
+    shared_buf->share_with(server_pid());
     ASAPI_ClientMessage request;
     request.type = ASAPI_ClientMessage::Type::PlayBuffer;
     request.play_buffer.buffer_id = shared_buf->shared_buffer_id();

Libraries/LibC/SharedBuffer.cpp

@@ -3,10 +3,10 @@
 #include <stdio.h>
 #include <unistd.h>
 
-RefPtr<SharedBuffer> SharedBuffer::create(pid_t peer, int size)
+RefPtr<SharedBuffer> SharedBuffer::create_with_size(int size)
 {
     void* data;
-    int shared_buffer_id = create_shared_buffer(peer, size, &data);
+    int shared_buffer_id = create_shared_buffer(size, &data);
     if (shared_buffer_id < 0) {
         perror("create_shared_buffer");
         return nullptr;
@@ -14,6 +14,16 @@ RefPtr<SharedBuffer> SharedBuffer::create(pid_t peer, int size)
     return adopt(*new SharedBuffer(shared_buffer_id, size, data));
 }
 
+bool SharedBuffer::share_with(pid_t peer)
+{
+    int ret = share_buffer_with(shared_buffer_id(), peer);
+    if (ret < 0) {
+        perror("share_buffer_with");
+        return false;
+    }
+    return true;
+}
+
 RefPtr<SharedBuffer> SharedBuffer::create_from_shared_buffer_id(int shared_buffer_id)
 {
     void* data = get_shared_buffer(shared_buffer_id);

Libraries/LibC/SharedBuffer.h

@@ -5,10 +5,11 @@
 
 class SharedBuffer : public RefCounted<SharedBuffer> {
 public:
-    static RefPtr<SharedBuffer> create(pid_t peer, int);
+    static RefPtr<SharedBuffer> create_with_size(int);
     static RefPtr<SharedBuffer> create_from_shared_buffer_id(int);
     ~SharedBuffer();
 
+    bool share_with(pid_t);
     int shared_buffer_id() const { return m_shared_buffer_id; }
     void seal();
     int size() const { return m_size; }

Libraries/LibC/unistd.cpp

@@ -423,9 +423,15 @@ int read_tsc(unsigned* lsw, unsigned* msw)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
-int create_shared_buffer(pid_t peer_pid, int size, void** buffer)
+int create_shared_buffer(int size, void** buffer)
 {
-    int rc = syscall(SC_create_shared_buffer, peer_pid, size, buffer);
+    int rc = syscall(SC_create_shared_buffer, size, buffer);
+    __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
+int share_buffer_with(int shared_buffer_id, pid_t peer_pid)
+{
+    int rc = syscall(SC_share_buffer_with, shared_buffer_id, peer_pid);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 

Libraries/LibC/unistd.h

@@ -21,7 +21,8 @@ int gettid();
 int donate(int tid);
 int create_thread(int (*)(void*), void*);
 void exit_thread(int);
-int create_shared_buffer(pid_t peer_pid, int, void** buffer);
+int create_shared_buffer(int, void** buffer);
+int share_buffer_with(int, pid_t peer_pid);
 void* get_shared_buffer(int shared_buffer_id);
 int release_shared_buffer(int shared_buffer_id);
 int seal_shared_buffer(int shared_buffer_id);

Libraries/LibGUI/GClipboard.cpp

@@ -38,7 +38,7 @@ void GClipboard::set_data(const StringView& data)
 {
     WSAPI_ClientMessage request;
     request.type = WSAPI_ClientMessage::Type::SetClipboardContents;
-    auto shared_buffer = SharedBuffer::create(GWindowServerConnection::the().server_pid(), data.length() + 1);
+    auto shared_buffer = SharedBuffer::create_with_size(data.length() + 1);
     if (!shared_buffer) {
         dbgprintf("GClipboard::set_data() failed to create a shared buffer\n");
         return;
@@ -48,6 +48,7 @@ void GClipboard::set_data(const StringView& data)
     else
         ((u8*)shared_buffer->data())[0] = '\0';
     shared_buffer->seal();
+    shared_buffer->share_with(GWindowServerConnection::the().server_pid());
     request.clipboard.shared_buffer_id = shared_buffer->shared_buffer_id();
     request.clipboard.contents_size = data.length();
     auto response = GWindowServerConnection::the().sync_request(request, WSAPI_ServerMessage::Type::DidSetClipboardContents);

Libraries/LibGUI/GWindow.cpp

@@ -600,8 +600,9 @@ NonnullRefPtr<GraphicsBitmap> GWindow::create_backing_bitmap(const Size& size)
     ASSERT(!size.is_empty());
     size_t pitch = round_up_to_power_of_two(size.width() * sizeof(RGBA32), 16);
     size_t size_in_bytes = size.height() * pitch;
-    auto shared_buffer = SharedBuffer::create(GWindowServerConnection::the().server_pid(), size_in_bytes);
+    auto shared_buffer = SharedBuffer::create_with_size(size_in_bytes);
     ASSERT(shared_buffer);
+    shared_buffer->share_with(GWindowServerConnection::the().server_pid());
     auto format = m_has_alpha_channel ? GraphicsBitmap::Format::RGBA32 : GraphicsBitmap::Format::RGB32;
     return GraphicsBitmap::create_with_shared_buffer(format, *shared_buffer, size);
 }